The broad objectives of this project are (a) to study the relationship between enzyme structure and function, (b) to study the regulation of enzyme activity at a molecular level and, (c) to study the regulation of biosynthesis of enzymes. In order to carry out these studies the TPN plus-specific isocitrate dehydrogenases from the nitrogen fixing bacterium Azotobacter vinelandii and the photosynthetic bacterium Rhodopseudomonas spheroides will be used as models. These studies will employ immunochemical techniques and immobilized enzymes. The broad objectives outlined above have further significance in leading to a better understanding of the regulation and control of biological processes.